A number of factors drive the period of time and cost required for new drug development. The discovery process, which formerly dominated time to market, has undergone a revolution due to techniques such as combinatorial chemistry and high throughput screening. The regulatory phase, which also previously lengthened drug development and marketing, has been reduced due to FDA reforms and European Union harmonization. Currently, human clinical trials have become the main bottleneck in getting a drug to market. It is estimated that the time required for clinical trials is roughly fifty percent (or 7.5 years) of the 15 years often required for the average new drug to come to market.
In U.S. pharmaceutical companies, a large percentage of total annual pharmaceutical research and development funds is spent on human clinical trials. Spending on clinical trials is growing at approximately fifteen percent per year, almost fifty percent above the industry's sales growth rate. Trials are growing both in number and complexity. For example, the average new drug submission to the U.S. Food and Drug Administration (FDA) now contains more than double the number of clinical trials, more than triple the number of patients, and more than a fifty percent increase in the number of procedures per trial, since the early 1980s.
One difficulty with conducting clinical trials is the selection of suitable subjects for the clinical trial. Not all subjects that have a particular disease will respond to a given therapy. For example, for every 100 node-negative breast cancer patients only a small fraction of patients are likely to benefit from the relatively toxic regimen. See Morrow and Krontiras, 2001, J. Natl. Cancer Inst. Monogr. 30:109-113; and Abrams, 2001, Breast Cancer 8:298-304. Similarly, for every 100 node-negative patients undergoing a Whipple procedure for pancreatic cancer at best only 20 survive 5 years or longer. See Yeo and Cameron, 1999, Curr. Probl. Surg. 36:59-152. Thus, failure to make rational clinical trial enrollment decisions can cause a clinical trial to fail for a given therapy, even in instances where the therapy has, in fact, significant efficacy in some populations.
To ensure the success of such clinical trials, what is needed in the art are systems and methods for identifying subjects that are suitable for clinical trials.